Merge rows from 2 sorted streams and output joined rows with matched key fields. Use this instead of hash join is
both your input streams are too big to fit in memory. Note that both the inputs must be sorted on the join key.
This is a first prototype implementation that only handles two streams and inner join. It also always outputs all
values from both streams. Ideally, we should: 1) Support any number of incoming streams 2) Allow user to choose the
join type (inner, outer) for each stream 3) Allow user to choose which fields to push to next step 4) Have multiple
output ports as follows: a) Containing matched records b) Unmatched records for each input port 5) Support incoming
rows to be sorted either on ascending or descending order. The currently implementation only supports ascending